What is a servo press?

A servo press uses servo motors for precise force and position control during forming operations.

How do I calculate servo press tonnage?

Use our free tonnage calculator at servopress.club/tonnage-calculator.html

Aerospace titanium forming on servo - anyone doing this?

anna_plc

We got a quote request for aerospace titanium forming on a servo press. Never done titanium before — our experience is all steel and aluminum. Is this even feasible on a standard servo press or do we need specialized equipment?

The parts are Ti-6Al-4V brackets, 1.2mm thick, relatively simple bends but tight tolerances and strict surface finish requirements (aerospace spec). Volume is low — maybe 5000 parts/year.

My main concerns are springback (I've heard titanium is terrible for this), die wear, and whether we need heated dies. Our press is a 200T servo, currently set up for cold forming only.

Anyone forming titanium on servo presses? What am I getting into?

yuki_rd

Titanium forming on servo press is viable but you need to understand the temperature sensitivity. Ti-6Al-4V formability improves dramatically above 300?C. Some shops use heated dies (warm forming) on servo presses to get the best of both worlds —servo precision with improved formability. The servo's slow forming speed also reduces adiabatic heating at the tool-material interface.

toolndye_dave

Die material for titanium is critical. Standard D2 tool steel galls against titanium within 1000 hits. We use carbide inserts or TiAlN-coated tool steel for titanium forming dies. The coating cost adds 30% to the die but extends life from 1000 to 50,000+ hits. Without proper die material, you'll be re-polishing dies every shift.

carlos_mx

We ran Ti-6Al-4V brackets for a landing gear subassembly on our 200T servo — about 8 months of production before the contract ended. Few things I learned the hard way:

Springback compensation is the real challenge. We ended up overbending 8-12 degrees depending on the flange geometry, and even then we had to do a restrike operation on about 40% of parts. The servo dwell at BDC helped — 200ms hold under load reduced springback by maybe 20% compared to a quick hit, but it doesn't eliminate it. We programmed a 2-step form: initial hit to 95% depth, 100ms pause, then final press to full depth. That stress-relaxation trick got our Cpk from 0.9 to 1.4 on the critical angle dimension.

On the die coating question — we tried TiAlN first and it worked OK but started showing micro-galling around 30K hits. Switched to AlCrN (Balinit Helica from Oerlikon) and got past 80K with no rework. The extra $4K per insert was nothing compared to the downtime for repolishing.

Lube is non-negotiable. We used Fuchs Renoform Ti-35 applied by roller coater before the press. Chlorinated lubes are banned for aerospace titanium (hydrogen embrittlement risk), so you need a purpose-made titanium forming lubricant. Don't let anyone tell you dry film will work for anything beyond shallow draws.

Speed: we ran at 8-12 SPM for forming stations. Could have gone faster mechanically but the heat buildup at the punch nose was causing surface discoloration above 15 SPM even with lube. Aerospace specs (AMS 4911) have strict surface condition requirements so we played it safe.

toolndye_dave

We quoted a titanium job once and passed. The tooling cost alone was 3x what we'd spend on steel. If the volumes are there it makes sense but for short runs the economics are tough.

lisaQ_metrology

Coming at this from the metrology side rather than the press side ??we measure aerospace Ti-6Al-4V parts after stamping for a couple of suppliers and the quality story is what kills most servo programs, not the press capability itself.

Springback on Ti is rate-dependent in a way that aluminum and steel are not. We see 12-18% angular springback at conventional rates and 8-12% when the bottom of the stroke is held above 800ms with active form-pressure. The servo's ability to dwell under load is the only reason this becomes economically viable. On a mechanical press you simply cannot dwell long enough.

The other thing nobody mentions: temperature. Ti work-hardens fast and the part comes out of the die at 60-90?C even at low rates. Dimensional inspection inside the first 20 minutes after forming will read 0.05-0.10mm tighter than the stabilized part. We've had RFQ disputes over this ??supplier measures hot, customer measures 24h cold, both are right and both are wrong. Standardize the inspection delay before signing the FAI plan.

Lubrication is the silent variable. Boron nitride dry-film works for shallow forms; for anything deeper you want a wet film with EP additives rated for 600+ MPa interface pressure. Galling on the punch nose is the failure mode, and it shows up as a periodic 0.02mm dimensional shift on the inspection charts long before the operator sees a mark on the part.

It's doable. It just isn't aluminum-with-extra-tonnage.